Digital e8-vsb reception system and e8-vsb data demultiplexing method

ABSTRACT

A method of processing a digital television (DTV) signal is disclosed. Herein, the DTV signal is generated by performing Reed-Solomon (RS) encoding on additional data, multiplexing the RS-encoded additional data with main data, RS encoding the multiplexed additional and main data, interleaving the RS-encoded additional and main data, trellis encoding the interleaved additional and main data, and transmitting a Radio Frequency (RF) DTV signal including the trellis-encoded additional and main data. The method to process the DTV signal includes receiving the DTV signal including the additional data multiplexed with the main data through an antenna, in which signaling information is periodically inserted in the additional data. The received DTV signal is demodulated including performing channel equalization on the demodulated DTV signal. Trellis decoding is performed on the channel-equalized DTV signal. Further, the additional data from the trellis-decoded DTV signal is extracted including removing dummy data from the extracted additional data.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/546,490 filed on Aug. 24, 2009, currently pending, which is acontinuation of U.S. patent application Ser. No. 10/995,768 filed onNov. 22, 2004, now U.S. Pat. No. 7,599,348, which is acontinuation-in-part (CIP) of U.S. patent application Ser. No.10/701,916 filed on Nov. 4, 2003, now U.S. Pat. No. 7,450,613, andclaims the benefit of earlier filing date and right of priority toKorean Application No. 10-2003-0083688, filed on Nov. 24, 2003, thecontents of which are incorporated by reference herein in theirentirety.

BACKGROUND

1. Field of the Invention

The present invention relates to an enhanced 8-VSB reception system andE8-VSB data demultiplexing method, by which a plurality of enhanceddata, which are encoded at different code rates and are multiplexed withMPEG data encoded by the previous ATSC 8VSB system to be transmitted,can be received.

2. Discussion of the Related Art

Generally, the United States of America (U.S.A.) has adopted the ATSC(advanced television systems committee) 8VSB (vestigial sideband)transmission system as standards for terrestrial digital broadcasting in1995 and has started the broadcasting since 1998. The Republic of Koreahas adopted the standards of the ATSC 8VSB transmission system and hasstarted its experimental broadcasting on May, 1995. The experimentalbroadcasting was switched to test broadcasting systems on Aug. 31, 2000,and the regular broadcasting has been broadcasted by major broadcastingstations since October, 2001.

FIG. 1 is a block diagram of an ATSC 8VSB transmission system accordingto a related art. Referring to FIG. 1, an ATSC data randomizer 101randomizes inputted MPEG video/voice data to output to a Reed-Solomoncoder 102. The Reed-Solomon coder 102 performs Reed-Solomon coding onthe randomized data, adds 20-byte parity code to the coded data, andthen outputs the corresponding data to a data interleaver 103. The datainterleaver 103 performs interleaving on the data outputted from theReed-Solomon coder 102 to change a sequence of the data and then outputsthe interleaved data to a trellis coder 104. The trellis coder 104converts the interleaved data to symbols from bytes and then performstrellis coding on the converted data to output to a multiplexer 105. Themultiplexer 105 multiplexes a trellis-coded symbol column with syncsignals to output to a pilot inserter 106. The pilot inserter 106 adds apilot signal to the multiplexed symbol column to output to a VSBmodulator 107. The VSB modulator 107 modulates the symbol columnoutputted from the pilot inserter 106 into an 8VSB signal of anintermediate frequency band to output to an RF converter 108. And, theRF converter 108 converts the received 8VSB signal of the intermediatefrequency band to an RF band signal to transmit via antenna.

The ATSC 8VSB transmission system developed for the HD (high definition)broadcast transmits MPEG-2 digital video and Dolby digital sound.Recently, as the Internet globally prevails in use, the demand forinteractive broadcast is rising, and various supplementary services arerequested. In order to meet such demands, many efforts are made todevelop the system enabling to provide separate supplementary servicesas well as the MPEG-2 digital video and Dolby digital sound on the samechannel.

In this case, unlike the normal video/sound data, the supplementary datasuch as a program execution file, stock information, and the like shouldbe transmitted with a lower error rate. In case of the video/sound data,errors failing to be perceptible to human eyes and ears are no big deal.Yet, in case of the supplementary data, one bit error occurrence mayraise a serious problem.

Hence, in a new E8-VSB transmission system compatible with the previousATSC 8VS system, supplementary data are coded by ½ and ¼ code rates,respectively, the supplementary data are multiplexed by 164-byte packetunit according to a previously determined multiplexing format, themultiplexed data are further pre-processed to output as an MPEGtransport packet format, the pre-processed enhanced data are multiplexedby 188-byte packet unit according to the previously determinedmultiplexing format, and the multiplexed data by 188-byte packet unitare then transmitted. Such technology has been filed by the presentapplicant (Korean Patent Application No. 10-2003-0017834, filed on Mar.21, 2003).

In the applicant's previous patent application, data are divided intomain data and enhanced data. The main data mean the foregoing-explainedprevious MPEG-2 video and Dolby digital sound data. And, the enhanceddata mean ½ enhanced data coded at ½ code rate and ¼ enhanced data codedat ¼ code rate. In the applicant's previous patent application, the ½enhanced data and the ¼ enhanced data are called ½ supplementary dataand ¼ supplementary data, respectively. Yet, their meanings areidentical to each other.

For convenience of explanation in the following description, asexplained in applicant's previous patent application, a transmittedsignal resulting from multiplexing enhanced data and main data (ornormal data) is called an enhanced 8-VSB (hereinafter abbreviatedE8-VSB) signal. Besides, the enhanced data and the main data can be usedas the enhanced data and the main data, respectively.

FIG. 2 is a block diagram of a general ATSC 8VSB receiver.

Referring to FIG. 2, once a VSB-modulated RF signal is received viaantenna, an RF tuner 201 selects an RF signal of a specific channel onlyby tuning and then converts it to an IF signal to output to an IF mixer202. The IF mixer 202 down-coverts the IF signal outputted from thetuner 201 to a near baseband (BB) signal to output to a demodulator 203.The demodulator 203 performs VSB demodulation on the near BB signal tooutput to an equalizer 204.

The equalizer 204 compensates channel distortion included in theVSB-demodulated signal to output to an 8VSB channel decoder 205. The8VSB channel decoder 205 converts the channel distortion compensatedsignal to an MPEG transport (TP) type signal to output.

However, in the general ATSC 8VSB receiver shown in FIG. 2, in case thatthe E8-VSB signal corresponding to the multiplexed signal of theenhanced data and the main data is transmitted, the enhanced datapackets will be recognized as null packets via PID (PacketIdentification) of MPEG transport header and gracefully discarded.Therefore the legacy ATSC 8-VSB receiver will receive the main data anddiscard the enhanced data as null packets.

SUMMARY

Accordingly, the present invention is directed to a method of processinga digital television (DTV) signal. Herein, the DTV signal is generatedby performing Reed-Solomon (RS) encoding on additional data,multiplexing the RS-encoded additional data with main data, RS encodingthe multiplexed additional and main data, interleaving the RS-encodedadditional and main data, trellis encoding the interleaved additionaland main data, and transmitting a Radio Frequency (RF) DTV signalincluding the trellis-encoded additional and main data. The method toprocess the DTV signal includes receiving the DTV signal including theadditional data multiplexed with the main data through an antenna, inwhich signaling information is periodically inserted in the additionaldata. The received DTV signal is demodulated including performingchannel equalization on the demodulated DTV signal. Trellis decoding isperformed on the channel-equalized DTV signal. Further, the additionaldata from the trellis-decoded DTV signal is extracted including removingdummy data from the extracted additional data.

An object of the present invention is to provide an enhanced 8-VSBreception system and E8-VSB data demultiplexing method, by which anenhanced VSB signal can be stably received as well as a previous ATSC8VSB signal.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, anE8-VSB reception system according to the present invention, whichreceives an E8-VSB signal transmitted from an E8-VSB transmission systemwhich multiplexes a first enhanced data coded at ½ code rate and asecond enhanced data coded at ¼ code rate by 164-byte packet unitaccording to a multiplexing format of E8-VSB map information inserted ina reserved area of a field sync signal and further pre-processes themultiplexed enhanced data packets to output as 188-byte transport packetand multiplexes the pre-processed enhanced data and a normal data by188-byte transport packet unit according to the multiplexing format ofthe E8-VSB map information inserted in the reserved area of the fieldsync signal, includes a tuner receiving an E8-VSB modulated RF signalvia antenna, the tuner selecting an RF signal of a specific channel bytuning, the tuner converting the selected RF signal to an IF signal tooutput, a demodulator converting the IF signal outputted from the tunerto a baseband signal to output, an E8-VSB map recovery detecting thefield sync signal and a field identifying signal within a frame from anoutput of the demodulator by performing frame sync recovery, the E8-VSBmap recovery extracting to decode the E8-VSB map information inserted inthe reserved area of the field sync signal using the detected field syncand identifying signals, the E8-VSB map recovery generating variouskinds of E8-VSB data attribute, a channel equalizer compensating channeldistortion included in the VSB-modulated signal by receiving the datamodulator output and the E8-VSB data attribute of the E8-VSB maprecovery, and an E8-VSB channel decoder/demultiplexer decoding a normaldata, a first enhanced data, and a second enhanced data from a signalequalized in the channel equalizer using the E8-VSB map information ofthe E8-VSB map recovery, the E8-VSB data attributes, and the field syncsignal.

The E8-VSB map information is Kerdock-coded to be inserted in thereserved area of the field sync signal and includes information of eachpacket number of the first and second enhanced data transmitted on onefield, the multiplexing format of the first and second enhanced data,and the multiplexing format of the enhanced data and the main data.

The E8-VSB map recovery includes a frame sync recovery detecting thefield sync signal and the field identifying signal indicating an even orodd field by performing frame synchronization from data symbolsoutputted from the demodulator, a map information extractor extractingthe E8-VSB map information inserted in the field sync signal from thedata symbols outputted from the demodulator using the field sync signal,a Kerdock decoder decoding the extracted map information by Kerdockdecoding algorithm, a current map decider deciding the E8-VSB mapinformation of a current field from the Kerdock-decoded E8-VSB mapinformation by the field sync signal and the field identifying signal,and an E8-VSB data attribute generator generating the E8-VSB dataattributes indicating attributes of a symbol or a byte unit of theE8-VSB data by the E8-VSB map information of the current field and thefield sync signal.

The E8-VSB data attribute generator includes a main and enhanced muxpacket processor generating to output a 188-byte attribute packetincluding attribute information of an E8-VSB data of byte unit byreceiving the E8-VSB map information of the current field outputted fromthe current map decider and the field sync signal outputted from theframe sync recovery, an ATSC RS coder outputting a 207-byte attributepacket by discarding the first byte of an input packet corresponding to0×47 MPEG sync byte and adding 20 bytes having an attribute of a normaldata to the 188-byte attribute packet, an ATSC data interleaverperforming ATSC data byte interleaving on the 207-byte attribute packetto output by byte unit, and a byte-symbol converter converting theinterleaved data of the byte unit to a symbol unit to output as theE8-VSB symbol attribute.

The main and enhanced mux packet processor includes an enhanced packetgenerator generating an attribute packet of 164-byte unit having theattribute information only indicating the first or second enhanced dataaccording to distribution formations and rates of first and secondenhanced data packets of the current field within the E8-VSB mapinformation of the current field, a null enhanced RS coder expanding 20bytes by copying the attribute of each of the packets to an enhanceddata attribute packet having the attribute information of the enhanceddata outputted from the enhanced packet generator, an enhanced datainterleaver performing enhanced data interleaving on data outputted fromthe null enhanced RS coder, a null-bit expander inserting a null bit inan interleaved byte outputted from the enhanced data interleaver to fitthe first and second enhanced data to expand, a null MPEG headerinserter inserting a byte of a normal data attribute corresponding to anMPEG header of 4 bytes in front of each 184 bytes outputted from thenull bit expander, and a main and enhanced packet multiplexermultiplexing to output a normal data packet and an enhanced data packetoutputted from the null MPEG header inserter by 188-byte packet unitusing the map information of the current field and the field syncsignal.

The main and enhanced packet generator seeks a number (H) of firstenhanced data of 164-byte packet unit and a number (Q) of secondenhanced data of 164-byte packet unit from E8-VSB map information basedon the field sync signal outputted from E8-VSB map recovery to find anumber (2P) of packets of 188-byte unit allocated to enhanced data inone VSB field (2P=2H+4Q), and the main and enhanced packet multiplexerdistributes to multiplex normal data packets and enhanced data packetsby a distribution method selection included in the E8-VSB mapinformation.

The E8-VSB channel decoder/demultiplexer includes a main data decoderperforming Viterbi decoding, 12-way deinterleaving, ATSC data bytedeinterleaving, ATSC RS decoding, and ATSC data derandomizing on theequalized data output according to the E8-VSB data attribute, and anenhanced data decoder decoding to separate the first and second enhanceddata by sequentially performing ATSC parity removal, ATSC dataderandomizing, null bit removal, enhanced data deinterleaving, enhancedRS decoding, and enhanced packet demultiplexing on the ATSC datadeinterleaved E8-VSB data outputted from the main data decoder by packetunit.

And, the enhanced data decoder includes an ATSC parity remover removingan ATSC RS parity portion from the ATSC byte deinterleaved packet dataoutputted from the main data decoder, an ATSC data derandomizerperforming the ATSC data derandomizing on the ATSC RS parity portionremoved data, a main and enhanced mux packet processor generating tooutput an attribute packet including attribute information of an E8-VSBdata of byte unit by receiving the E8-VSB map information of a currentfield and the field sync signal, a null bit remover removing entire bitsof the normal data byte and insignificant bits of the first and secondenhanced data bytes to reconfigure the data of the byte unit into afirst significant enhanced byte and a second significant enhanced byteby using E8-VSB byte attribute outputted from the main and enhanced muxpacket processor, an enhanced data deinterleaver performing the enhanceddata deinterleaving on enhanced data of the byte unit configured withsignificant bits outputted from the null bit remover, an enhanced RSdecoder performing the enhanced RS decoding on the enhanceddeinterleaved data, and an enhanced packet demultiplexer separating theenhanced RS decoded data into a first enhanced data packet and a secondenhanced data packet to output using the E8-VSB map information and thefield sync signal outputted from the E8-VSB map recovery.

In another aspect of the present invention, an E8-VSB datademultiplexing method of an E8-VSB reception system which receives anE8-VSB signal transmitted from an E8-VSB transmission system, the E8-VSBtransmission system which multiplexes a first enhanced data coded at ½code rate and a second enhanced data coded at ¼ code rate by 164-bytepacket unit according to a multiplexing format of E8-VSB map informationinserted in a reserved area of a field sync signal and furtherpre-processes the multiplexed enhanced data packets to output as188-byte transport packet and multiplexes the pre-processed enhanceddata and a normal data by 188-byte transport packet unit according tothe multiplexing format of the E8-VSB map information inserted in thereserved area of the field sync signal. The E8-VSB data demultiplexingmethod of the E8-VSB reception system includes a step (a) of detectingthe field sync signal and a field identifying signal indicating an evenor odd field within a frame from received and demodulated E8-VSB data byperforming frame sync recovery, a step (b) of extracting to decode theE8-VSB map information inserted in the reserved area of the field syncsignal using the detected field sync and identifying signals detected inthe step (a) and generating various kinds of E8-VSB data attributes, astep (c) of compensating channel distortion included in theVSB-modulated signal by receiving the various kinds of the E8-VSB dataattributes, and a step (d) of receiving the E8-VSB data attributessynchronized with an E8-VSB symbol equalized data in the step (c) anddecoding a normal data, a first enhanced data, and a second enhanceddata from the equalized signal using the E8-VSB map information of theE8-VSB map recovery, the E8-VSB data attributes, and the field syncsignal.

The step (b) includes a step (b-1) of extracting the E8-VSB mapinformation inserted in the field sync signal from the data symbolsoutputted from the demodulator using the field sync signal, a step (b-2)of decoding the extracted map information by Kerdock decoding algorithm,a step (b-3) of deciding the E8-VSB map information of a current fieldfrom the Kerdock-decoded E8-VSB map information by the field sync signaland the field identifying signal, and a step (b-4) of generating theE8-VSB data attributes by the E8-VSB map information of the currentfield and the field sync signal.

The step (b-4) includes the steps of generating to output a 188-byteattribute packet including attribute information of an E8-VSB data byreceiving the E8-VSB map information of the current field outputted fromthe current map decider and the field sync signal outputted from the(b-3) step, outputting a 207-byte attribute packet by discarding thefirst byte of an input packet corresponding to 0×47 MPEG sync byte andadding 20 bytes having an attribute of a normal data to the 188-byteattribute packet, performing ATSC data byte interleaving on the 207-byteattribute packet to output by byte unit, and converting the interleaveddata of the byte unit to a symbol unit to output as the E8-VSB datasymbol attribute.

The attribute packet generating step includes the steps of generating anenhanced data attribute packet of 164-byte unit having the attributeinformation only indicating the first or second enhanced data accordingto distribution formations and rates of first and second enhanced datapackets of the current field within the E8-VSB map information of thecurrent field, expanding 20 byte by copying the attribute of each of thepackets to the enhanced data attribute packet having the attributeinformation of the enhanced data only, performing enhanced datainterleaving on parity-expanded data outputted from the expanding step,expanding an interleaved byte outputted from the enhanced datainterleaving step by inserting a null bit in the interleaved byte to fitthe first and second enhanced data, inserting a 4-byte MPEG header valueindicating a normal data byte in each 184 bytes outputted from the nullbit expanding step, and multiplexing to output a normal data packet andan enhanced data packet having the null MPEG header inserted by 188-bytepacket unit using the map information of the current field and the fieldsync signal.

And, the step (d) includes a step (d-1) of main data decoding bysequentially performing Viterbi decoding, 12-way deinterleaving, ATSCdata byte deinterleaving, ATSC RS decoding, and ATSC data derandomizingon the equalized E8-VSB symbol according to the E8-VSB data attributes,and a step (d-2) of decoding to separate the first and second enhanceddata by sequentially performing ATSC parity removal, ATSC dataderandomizing, null bit removal, enhanced data interleaving, enhanced RSdecoding, and enhanced packet demultiplexing on the ATSC datadeinterleaved E8-VSB data outputted by packet unit in the step (d-1).

In the enhanced packet demultiplexer, a number (H) of first enhanceddata packets of 164-byte unit and a number (Q) of second enhanced datapackets of 164-byte unit are sought from the E8-VSB map outputted fromthe E8-VSB map recovery block.

In the null bit remover of the enhanced data decoder, the normal datapackets, the MPEG headers added to the enhanced data packets and thenull bits inserted for byte expansion at the transmitter are removedusing the E8-VSB map, the E8-VSB data attributes and field sync signaloutputted from the E8-VSB map recovery.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiments of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 is a block diagram of an ATSC 8VSB transmission system accordingto a related art;

FIG. 2 is a block diagram of a general ATSC 8VSB receiver;

FIG. 3 is a block diagram of an E8-VSB transmission system according tothe present invention;

FIG. 4 is a detailed block diagram of a main and enhanced mux packetprocessor of the system in FIG. 3;

FIG. 5A is a structural diagram of a data frame of ATSC 8VSBtransmission system;

FIG. 5B is a structural diagram of a field sync signal in FIG. 5A;

FIG. 6 is a detailed block diagram of an E8-VSB pre-processor in FIG. 4;

FIG. 7A is a diagram of multiplexing ½ enhanced data packets and ¼enhanced data packets by a uniform distribution;

FIG. 7B is a diagram of multiplexing ½ enhanced data packets and ¼enhanced data packets by a grouping distribution;

FIG. 7C is a diagram of multiplexing ½ enhanced data packets and ¼enhanced data packets by an alternative distribution;

FIG. 8 is a block diagram of an E8-VSB reception system according to thepresent invention;

FIG. 9 is a detailed block diagram of an E8-VSB map recovery unit inFIG. 8;

FIG. 10 is a detailed block diagram of an E8-VSB data attributegenerator in FIG. 9;

FIG. 11 is a detailed block diagram of an E8-VSB channeldecoder/demultiplexer in FIG. 8;

FIG. 12 is a detailed block diagram of a main and enhanced mux packetprocessor in FIG. 10 and FIG. 11;

FIG. 13 is a diagram of byte expansion and removal of ½ enhanced data;

FIG. 14 is a diagram of byte expansion and removal of ¼ enhanced data;

FIG. 15A is a diagram of a group distribution in multiplexing ½ enhanceddata packets and ¼ enhanced data packets;

FIG. 15B is a diagram of an alternative distribution in multiplexing ½enhanced data packets and ¼ enhanced data packets;

FIG. 16A is a diagram of a multiplexing format of normal data packetsand enhanced data packets, in which an exemplary distribution having apattern according to conditions is shown; and

FIG. 16B is a diagram of a multiplexing format of normal data packetsand enhanced data packets, in which an exemplary uniform distribution isshown.

DETAILED DESCRIPTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

For the understanding of an E8-VSB reception system of the presentinvention, the E8-VSB transmission system and multiplexing processdisclosed in the Korean Patent Application No. 10-2003-0017834 isexplained with reference to the attached drawings as follows.

First of all, in the Korean Patent Application No. 10-2003-0017834, therecent MPEG-4 video or various supplementary data (e.g., programexecution file, stock information, etc.) can be transferred via enhanceddata as well as the previous MPEG-2 video and Dolby sound data. In doingso, error correction encoding is additionally performed on the enhanceddata except main data. And, ½ enhanced data and ¼ enhanced data meandata on which encoding is additionally performed at ½ and ¼ code rates,respectively, unlike the main data. Hence, the enhanced data is providedwith reception performance superior to that of the main data in noisegenerated from channel and interference due to multi-path. Specifically,the ¼ enhanced data coded at ¼ code rate has performance more excellentthan that of the ½ enhanced data coded at ½ code rate.

Referring to FIG. 3, a main and enhanced mux packet processor 301multiplexes ½ enhanced data and ¼ enhanced data by 164-byte packet unitand further pre-processes the multiplexed enhanced data to output as a188-byte transport packet format and multiplexes the pre-processedenhanced data and main data by 188-byte packet unit again, and thenoutputs the data to a first encoding unit 302. The first encoding unit302 includes a randomizer 302-1, Reed-Solomon coder 302-2, and byteinterleaver 302-3 sequentially connected to an output end of the mainand enhanced mux packet processor 301. The first encoding unit 302sequentially performs data randomization, Reed-Solomon coding, and datainterleaving on a data packet outputted from the main and enhanced muxpacket processor 301 to output to an E8-VSB convolutional coder 303. TheE8-VSB convolutional coder 303 converts the interleaved data of byteunit outputted from the first encoding unit 302 to symbols, performsconvolutional coding on an enhanced data symbol only, converts thesymbol to data of byte unit, and then outputs the converted data to afirst decoding unit 304.

The first decoding unit 304 includes a byte deinterleaver 304-1,Reed-Solomon parity remover 304-2, and derandomizer 304-3 sequentiallyconnected to an output end of the E8-VSB convolutional coder 303. Thefirst decoding unit 304 sequentially performs data deinterleaving,Reed-Solomon parity removal, and derandomization on the data of byteunit outputted from the E8-VSB convolutional coder 303 to output to an8VSB transmission unit 100.

The 8VSB transmission unit 100 having the same configuration shown inFIG. 1 sequentially performs data randomization, Reed-Solomon coding,data interleaving, trellis coding, and the like again on the data ofwhich Reed-Solomon parity was removed by the first decoding unit 304. Inthe FIG. 3, ATSC derandomizer 304-3 of the first decoding unit 304 andATSC randomizer 101 of the 8VSB transmission unit 100 can be skippedtogether.

FIG. 4 is a detailed block diagram of the main and enhanced mux packetprocessor 301. After ½ enhanced data and ¼ enhanced data have beenmultiplexed by 164-byte packet unit and further pre-processed by theE8-VSB pre-processor, main data is multiplexed with the pre-processedenhanced data by 188-byte packet unit. In doing so, a frame configuringone picture in the VSB transmission system includes two data fields.Each of the data fields includes one field sync segment and 312 datasegments. And, one data segment includes a data segment sync signal of4-symbols and data of 828-symbols.

Referring to FIG. 4, a main data buffer 401 temporarily stores main datainputted as a packet of 188-byte unit and then outputs the main data toa main and enhanced packet multiplexer 405. A ½ enhanced data buffer 402temporarily stores ½ enhanced data inputted as a packet of 188-byteunit. A ¼ enhanced data buffer 403 temporarily stores ¼ enhanced datainputted as a packet of 188-byte unit and then outputs the data to anE8-VSB pre-processor 404.

The E8-VSB pre-processor 404 multiplexes the ½ enhanced data outputtedfrom the ½ enhanced data buffer 402 and the ¼ enhanced data outputtedfrom the ¼ enhanced data buffer 403 with each other by 164-byte packetunit according to a previously determined format, further pre-processesto the same structure of an MPEG transport packet of the main data, andthen outputs the converted data to the main and enhanced packetmultiplexer 405.

The main and enhanced packet multiplexer 405 multiplexes the main datapacket outputted from the main data buffer 401 and the enhanced datapacket outputted from the E8-VSB pre-processor 404 into 188-byte packetunits according to main/enhanced data multiplexing information insertedin the field sync signal.

In doing so, once the number of packets of the enhanced data to betransmitted on one VSB data field is determined, the E8-VSB transmissionsystem inserts main/enhanced data multiplexing map information(hereinafter referred to as E8-VSB map information) associated with themultiplexing format and the transport packet number of the enhanced datain an unused area within the field sync segment and then transmits thecorresponding signal. Hence, the E8-VSB reception system enables toperform accurate demultiplexing to correspond to the field sync.

FIG. 5A is a structural diagram of a data frame of an ATSC 8VSBtransmission system.

Referring to FIG. 5, one frame is divided into an odd field and an evenfield. Each of the fields is divided into three hundred thirteensegments. The 313 segments include one field sync segment containing atraining sequence signal and three hundred twelve data segments.

And, one segment includes 832-symbols. In this case, first 4-symbols inone segment construct a sync part and a first segment in each fieldbecomes a field sync part.

The field sync segment format is shown in FIG. 5B. A segment syncpattern exists in first 4-symbols, pseudo random sequences PN 511, PN63, PN 63, and PN 63 follow the segment sync pattern, and VSB modeassociated information exists in the next 24-symbols, in turn. In thiscase, a polarity of the second PN 63 among the three PN 63 sections isalternately changed. Namely, ‘1’ is changed into ‘0’ or ‘0’ is changedinto ‘1’. Hence, one frame can be divided into even and odd fieldsaccording to the polarity of the second PN 63.

Meanwhile, the rest 104-symbols following the 24-symbols where the VSBmode associated information exists are reserved. And, the last12-symbols data of the previous segment are copied to last 12-symbols ofthe reserved area.

In the present invention, E8-VSB map information including themultiplexing format and the main/enhanced data multiplexing informationassociated with the transport packet number of the enhanced data isinserted in the first 64-symbols of the reserved area within the fieldsync segment in FIG. 5B to be transmitted.

Namely, 64 two-level symbols of the reserved area within the field syncsegment are used for transmitting E8-VSB map information. The E8-VSB mapinformation is inserted by being coded as Kerdock (64,12). A polarity ofthe Kerdock code word becomes reversed in an even (negative PN 63) datafield. The Kerdock coding algorithm is known to public, of whichdetailed explanation will be skipped in the following.

FIG. 6 is a detailed block diagram of the E8-VSB pre-processor 404.

Referring to FIG. 6, a ½ MPEG packet converter 501 segments ½ enhanceddata inputted as packets of 188-byte unit into 164-byte units withoutdata alteration to output to an enhanced packet multiplexer 503. And, a¼ MPEG packet converter 502 segments ¼ enhanced data inputted as packetsof 188-byte unit into 164-byte units without data alteration to outputto the enhanced packet multiplexer 503.

The enhanced packet multiplexer 503 multiplexes the ½ and ¼ enhanceddata outputted from the ½ and ¼ MPEG packet converters 501 and 502 by164-byte packet unit according to E8-VSB map information within a fieldsync segment to output to an enhanced Reed-Solomon coder 504. Theenhanced Reed-Solomon coder 504 performs Red-Solomon coding on theenhanced data multiplexed in the enhanced packet multiplexer 503 andthen adds a parity code of 20 bytes thereto, thereby converting theenhanced data of 164-byte unit to a packet of 184-byte unit to output toan enhanced data interleaver 505. In order to enhance performanceagainst burst noise, the enhanced data interleaver 505 changes asequence of the data outputted from the enhanced Reed-Solomon coder 504and then outputs the sequence-changed data to a null-bit inserter 506.Subsequently, the null-bit inserter 506 inserts a null-bit correspondingto the ½ or ¼ enhanced data outputted from the enhanced data interleaver505 to expand a packet and then outputs the expanded packet to an MPEGheader inserter 507. The MPEG header inserter 507 inserts an MPEG headerof 4 bytes in a front portion of each 184 bytes of the enhanced datahaving the null-bit inserted by the null-bit inserter 506 to make aformat identical to that of the MPEG transport packet of the main dataand then outputs the corresponding data to the main and enhanced packetmultiplexer 405. This is to discard the packet by checking PID in casethat the previous VSB receiver receives the enhanced data packet Whenthe ½ enhanced data of 1 byte is inputted, the null-bit inserter 506inserts a null-bit between the respective bits to expand to 2 bytes.When the ¼ enhanced data of 1 byte is inputted, the null-bit inserter506 repeats each bit twice and inserts null-bits between the respectivebits to expand to 4 bytes. Such a null-bit will be replaced by a paritybit by an E8-VSB convolutional coder 303.

Moreover, the multiplexing information for multiplexing the ½ and ¼enhanced data in the enhanced packet multiplexer 503 of the E8-VSBpre-processor 404 and the multiplexing information for multiplexing themain data and the enhanced data in the main and enhanced packetmultiplexer 405 of the main and enhanced mux packet processor 301 iscalled the E8-VSB map information in the present invention. As mentionedin the foregoing description, the E8-VSB map information isKerdock-coded and then inserted in the reserved are (bit) within thefield sync segment to be transmitted.

Meanwhile, a method of multiplexing the ½ and ¼ enhanced data in theenhanced packet multiplexer 503 of the E8-VSB pre-processor 404 isexplained in detail as follows.

First of all, the numbers of ½ and ¼ enhanced data packets of 164-byteunit multiplexed in the enhanced packet multiplexer 503 within one VSBdata field will be defined as H and Q, respectively.

In this case, the null-bit inserter 506 of FIG. 6 inserts a null-bit tooutput 2 bytes in case of receiving the ½ enhanced data of 1 byte orinserts null-bits to output 4 bytes in case of receiving the ¼ enhanceddata of 1 byte. Since one VSB data field consists of three hundredtwelve data segments, a maximum value of ‘H’ becomes 156 (=312/2) if the½ enhanced data is multiplexed only to be transmitted. By the same rule,a maximum value of ‘Q’ becomes 78 (=312/4) in case of transmitting the ¼enhanced data only. Namely, if the ½ enhanced data is transmitted only,it is able to transmit maximum 156-packets (1-packet=164 bytes). And, ifthe ¼ enhanced data is transmitted only, it is able to transmit maximum78-packets (1-packet=164 bytes).

This can be generalized by the following equation.

N+2H+4Q=312

In this case, the number of data segments within one VSB field is 312resulting from adding the normal data packet number (N), the packetnumber (H) of a first enhanced data, and the packet number (Q) of asecond enhanced data to each other according to the above expression.

The Korean Patent Application No. 10-2003-0017834 has proposed methodsof multiplexing ½ and ¼ enhanced data packets in the enhanced packetmultiplexer 503 if the values of ‘H’ and ‘Q’ are determined.

The first method of uniform multiplexing, as shown in FIG. 7A, is tomultiplex the ½ and ¼ enhanced data packets with equal interval.

The second method of grouping multiplexing, as shown in FIG. 7B, is tomultiplex the ½ and ¼ enhanced data packets by grouping the ½ enhanceddata packets and the ¼ enhanced data packets separately. The ½ enhanceddata packets, as shown in FIG. 7B, are grouped for one data field to beoutputted and the ¼ enhanced data packets are then grouped for one datafield to be outputted.

And, the third method of alternate multiplexing, as shown in FIG. 7C, isto multiplex the ½ and ¼ enhanced data packets alternately. First ofall, the ½ and ¼ enhanced data packets, as shown in FIG. 7C, arealternately multiplexed. Once either the ½ or ¼ enhanced data packetsare completely multiplexed, the rest data packets are multiplexed.

Namely, FIGS. 7A to 7C show the methods of multiplexing the ½ and ¼enhanced data packets that will be transmitted on one VSB data field incase of H=8 and Q=2.

If the numbers H and Q of the ½ and ¼ enhanced data packets transmittedon one VSB data field are determined, the ½ enhanced data packet number,¼ enhanced data packet number, and E8-VSB map information associatedwith the format used for the multiplexing among the above-explainedmultiplexing methods are inserted in the reserved area within the fieldsync segment to transmit to the E8-VSB reception system and outputted tothe enhanced packet multiplexer 503 and the main and enhanced packetmultiplexer 405. The enhanced packet multiplexer 503 then multiplexesthe ½ and ¼ enhanced data packets by the multiplexing format accordingto the enhanced data multiplexing information. In doing so, the formatused for the multiplexing may be fixed to one of the multiplexingmethods (formats) or can be adaptively decided according to the numbersof the ½ and ¼ enhanced data packets multiplexed on one VSB data field.

In case that the E8-VSB transmission system according to the presentinvention adopts to use one of the three methods only, the values of ‘H’and ‘Q’ need to exist in the E8-VSB map information within the fieldsync signal only. Yet, in case that all of the three methods areoptionally used or in case that two of the three methods are optionallyused, the information indicating which method is used for thecorresponding multiplexing should be added to the E8-VSB map informationwithin the field sync signal.

Namely, the information for the transport packet numbers of the ½ and ¼enhanced data within one data field, the information indicating whichformat is adopted to multiplex the ½ and ¼ enhanced data, and theinformation indicating which format is used for multiplexing theenhanced data and the main data should be contained in the E8-VSB mapinformation inserted in the reserved area within the field sync segment.

FIG. 8 is a block diagram of an E8-VSB reception system according to thepresent invention for receiving an E8-VSB signal transmitted from theE8-VSB transmission system in FIGS. 3 to 7.

Referring to FIG. 8, an E8-VSB reception system according to the presentinvention includes a tuner 601, an IF mixer 602, a demodulator 603, anequalizer 604, an E8-VSB map recovery 605, and an E8-VSB channeldecoder/demultiplexer 606. Configurations and operations of the tuner601, IF mixer 602, and demodulator 603 are equivalent to those in FIG.2.

Namely, once an E8-VSB-modulated RF signal is received via antenna, thetuner 601 selects an RF signal of a specific channel only by tuning andthen converts it to an IF signal to output to the IF mixer 602. The IFmixer 602 down-coverts the IF signal outputted from the tuner 601 to anear baseband (BB) signal to output to the demodulator 603. Thedemodulator 603 performs VSB demodulation on the near BB signal tooutput to the equalizer 604 and the E8-VSB map recovery 605. The E8-VSBmap recovery 605 detects E8-VSB map information inserted in a reservedarea of a field sync segment to output to the equalizer 604 and theE8-VSB channel decoder/demultiplexer 606. The equalizer 604 receives thedecision feedback from the E8-VSB channel decoder/demultiplexer 606 atits end and the output of the E8-VSB map recovery 605 and thencompensates channel distortion included in the VSB-demodulated signal tooutput to the E8-VSB channel decoder/demultiplexer 606. Namely, theequalizer 604 performs enhanced equalization using the output of theE8-VSB map recovery 605 and more reliable symbol decisions from theE8-VSB channel decoder/demultiplexer 606.

FIG. 9 is a detailed block diagram of the E8-VSB map recovery 605.

Referring to FIG. 9, the E8-VSB map recovery 605 includes an E8-VSB mapextractor 701 extracting E8-VSB map information from data symbolsoutputted from the demodulator 603 or data symbols outputted from theenhanced equalizer 604, a Kerdock decoder 702 decoding the extractedE8-VSB map information by Kerdock decoding algorithm, a frame syncrecovery 704 performing frame synchronization from the data symbolsoutputted from the demodulator 603 or the data symbols outputted fromthe enhanced equalizer 604 to output a field sync signal and a fieldidentifying signal indicating an even or odd field, a current mapdeciding unit 703 deciding a current map by receiving the E8-VSB mapinformation decoded in the Kerdock decoder 702, the field sync signal,and the field identifying signal, and an E8-VSB data attribute generator705 generating attribute information of a current E8-VSB data accordingto the current map information and the field sync signal.

The E8-VSB map recovery 605 performs an operation of extracting theE8-VSB map information inserted in a field sync section by the E8-VSBtransmission system. The E8-VSB data attribute generator 705 of theE8-VSB map recovery 605 generates information indicating attributes ofthe respective E8-VSB data to provide to the equalizer 604 and theE8-VSB channel decoder/demultiplexer 606, thereby intending to enhanceperformance of both of the equalizer 604 and the E8-VSB channeldecoder/demultiplexer 606.

In order to receive the E8-VSB signal, the E8-VSB map recovery 605 isessential to the above-configured present invention. For reliabledetection of the E8-VSB map, E8-VSB map recovery 605 selectivelyreceives its input data between the input of the equalizer 604 and theoutput signal of the equalizer 604.

Meanwhile, explained in the following is an example that the E8-VSB maprecovery 605 utilizes the input/output signal of the equalizer.

The first method enables to selectively use the input or output signalof the equalizer 604 as the input data of the E8-VSB map recovery 605with reference to a presence or non-presence of operation of theequalizer 604 and an output SNR at the rear end of the equalizer. Thesecond method enables to elicit the E8-VSB map information of acurrently received signal by providing a pair of E8-VSB map recoveryunits to utilize reliability of outputs from a pair of the E8-VSB maprecovery units. And, the third method synchronizes signals of the inputand output sides of the equalizer 604 to use as the input data of theE8-VSB map recovery 605.

In doing so, a frame of the VSB signal should be synchronized so thatthe E8-VSB map recovery 605 can recognize the presence of the enhancedmode from the received signal. Hence, the frame sync recovery 704detects the field sync signal and the field identifying signalindicating whether the current field is the even or odd field byperforming frame synchronization from the inputted data symbols and thenoutputs them to the E8-VSB map extractor 701, the current map decidingunit 703, and the E8-VSB data attribute generator 705. Namely, it isable to detect whether the current field is the even or odd field usingthe polarity of the second PN 63 in the training signal of the fieldsync signal section.

The E8-VSB map extractor 701 receives the field sync signal from theframe sync recovery 704. If the inputted data symbol indicates the fieldsync signal, the E8-VSB map extractor 701 extracts the E8-VSB mapinformation included in the field sync signal section and then outputsthe extracted information to the Kerdock decoder 702.

In doing so, since the extracted E8-VSB map information was transmittedfrom the E8-VSB transmission system by being coded according to theKerdock coding algorithm clearly stated in the E8-VSB specification, theKerdock decoder 702 decodes the extracted E8-VSB map informationaccording to the Kerdock decoding algorithm to output to the current mapdeciding unit 703. The current map deciding unit 703 divides theKerdock-decoded E8-VSB map information into the even field E8-VSB mapinformation and the odd field E8-VSB map information by the field syncsignal and field identifying signal outputted from the frame syncrecovery 704 and then decides the E8-VSB map information of the currentfield again. Hence, the decided E8-VSB map information of the currentfield is simultaneously outputted to the E8-VSB channeldecoder/demultiplexer 606 and the E8-VSB data attribute generator 705.

The E8-VSB data attribute generator 705 generates signals indicating anattribute of E8-VSB data at the symbol, byte and packet level based onthe E8-VSB map information of the current field. Namely, the E8-VSB dataattribute generator 705 generates signals indicating whether the symbol,byte or packet is a normal data (or main data) or an enhanced data. Incase of the enhanced data, the E8-VSB data attribute generator 705generates attribute information of the enhanced data for indicatingwhether the enhanced data is ½ enhanced data or ¼ enhanced data and thenoutput the generated information to the equalizer 604 and the E8-VSBchannel decoder/demultiplexer 606.

FIG. 10 is a detailed block diagram of the E8-VSB data attributegenerator 705.

Referring to FIG. 10, the E8-VSB data attribute generator 705 includes amain and enhanced mux packet processor 801 receiving the E8-VSB mapinformation of the current field and the field sync signal to output a188-byte attribute packet containing the attribute informationidentifying the normal data, the %-rate enhanced data or the ¼-rateenhanced data, a null ATSC RS coder 802 outputting a 207-byte attributepacket by discarding the first byte of an input packet corresponding to0×47 MPEG sync byte and adding a parity amount of the ATSC RS coder,i.e., 20 bytes having the attribute of the normal data, to the 188-byteattribute packet, an ATSC data interleaver 803 interleaving the 207-byteattribute packet, and a byte-symbol converter 804 converting theinterleaved data of byte unit to data of symbol unit to output as anattribute of E8-VSB data symbol. The E8-VSB symbol attribute is providedto the enhanced equalizer 604 and the Viterbi decoder 901 of the E8-VSBchannel decoder/demultiplexer 606.

The above-configured E8-VSB data attribute generator 705, as shown inFIG. 10, generates the attribute information of each symbol in a mannerof using the field sync signal and the E8-VSB map information of thecurrent field.

Namely, the main and enhanced mux packet processor 801 receives thefield sync signal and the E8-VSB map information of the current field tooutput the attribute packet constructed with 188 bytes to the null ATSCRS coder 802. The attribute packet contains no data information but theattribute information per byte. And, the attribute also enables toidentify whether each byte is the byte of the normal data, the ½enhanced data coded at ½ code rate, or the ¼ enhanced data coded at ¼code rate. FIG. 12 is a detailed block diagram of the main and enhancedmux packet processor 801, which will be explained in detail later.

The null ATSC RS coder 802 outputs the 207-byte attribute packet to theATSC data interleaver 803 by discarding the first byte of an inputpacket corresponding to 0×47 MPEG sync byte and adding the parity amountof the ATSC RC coder, i.e., 20 bytes having the attribute of the normaldata, to the 188-byte attribute packet. The ATSC data interleaver 803performs ATSC data interleaving on the 207-byte attribute packet tooutput to the byte-symbol converter 804. The byte-symbol converter 804converts the interleaved data of byte unit to the data of symbol unit tooutput as an attribute of the E8-VSB data symbol. And, the E8-VSB datasymbol attribute is provided to the enhanced equalizer 604 and theViterbi decoder 901 of the E8-VSB channel decoder/demultiplexer 606.

The equalizer 604 receives each attribute of the currently inputted VSBsymbol from the E8-VSB map recovery 605, thereby enabling to exertequalization capability more enhanced than that of the conventionalequalizer. Moreover, by feeding back a symbol decision of the Viterbidecoder 901 of the E8-VSB channel decoder/demultiplexer 606 to theequalizer 604, it is able to enhance equalization performance. Namely,since the reliability of the enhanced symbol(s) is higher than that ofthe normal data symbol, the equalizer 604 enables to improve itsequalization performance using the two kinds of information (i.e.,E8-VSB data symbol attribute and symbol decision feedback from theViterbi decoder 901).

Meanwhile, the E8-VSB channel decoder/demultiplexer 606, as shown inFIG. 11, has a separate data path to receive an enhanced data as well asa normal data. Namely, by decoding or separating a reception signal in acorresponding mode using the E8-VSB map information and E8-VSB dataattributes indicating the multiplexing information of the currentlyreceived E8-VSB signal, the E8-VSB reception system enables to receive anormal data MPEG TPS #1, ½ enhanced data MPEG TPS #2, and ¼ enhanceddata MPEG TPS #3. In this case, the mode indicates one of normal data,the ½ enhanced data, and the ¼ enhanced data.

FIG. 11 is a detailed block diagram of the E8-VSB channeldecoder/demultiplexer 606.

Referring to FIG. 11, the E8-VSB channel decoder/demultiplexer 606includes a main data decoding unit 900 separating to decode the normaldata MPEG TPS #1 from an equalized signal and an enhanced data decodingunit 950 separating to decode the enhanced data and separating thedecoded data into the ½ enhanced data MPEG TPS #2 and the ¼ enhanceddata MPEG TPS #3. The main data decoding unit 900 is the same as achannel decoder of the legacy ATSC receiver, but the difference is thatthe Viterbi decoder 901 of the main decoding unit 900 decodes bothnormal data and enhanced data using E8-VSB data attributes of symbolunit from E8-VSB data attribute generator 705. The enhanced datadecoding unit 950 is a data path of decoding the ½ and ¼ enhanced data.

The main data decoding unit 900 includes a Viterbi decoder/12-way datainterleaver 901, an ATSC byte deinterleaver 902, an ATSC RS decoder 903,and an ATSC data derandomizer 904.

Namely, as is the same case of the conventional 8VSB channel decoder,the normal data symbol equalized in the equalizer 604 is decoded intothe normal data stream MPEG TPS #1 via the Viterbi decoder/12-waydeinterleaver 901, ATSC data byte deinterleaver 902, ATSC RS decoder903, and ATSC data derandomizer 904 of the main data decoding unit 900.The transmitted signal from the legacy ATSC 8VSB transmitter is decidedas the signal having normal data only by the E8-VSB map recovery and canbe received via the path of the main data decoding unit 900.

Yet, since the 8VSB signal and the enhanced VSB signal are multiplexedin case of the E8-VSB signal, there are two differences in the E8-VSBchannel decoder/demultiplexer 606 compared to the conventional ATSC 8VSBchannel decoder. One is that decoding appropriate for each E8-VSB symbolshould be performed in the Viterbi decoder based on the attribute ofE8-VSB symbol, and the other is that a separate data path for theenhanced data should exist.

The enhanced data decoding unit 950, which is the data path for decodingthe enhanced data, includes an ATSC RS parity removing unit 951, an ATSCdata derandomizer 952, a null-bit removing unit 953, an enhanced datadeinterleaver 954, an enhanced RS decoder 955, an enhanced packetdemultiplexer 956, and a main and enhanced mux packet processor 957.

Considering the E8-VSB channel decoder/demultiplexer 606 in FIG. 11, theE8-VSB symbol equalized in the equalizer 604 and the E8-VSB data symbolattribute generated from the E8-VSB map recovery 605 are synchronized tobe inputted to the Viterbi decoder/12-way deinterleaver 901.

In doing so, since the normal symbol and the enhanced symbol are mixedin the equalized symbol inputted to the Viterbi decoder/12-waydeinterleaver 901, the Viterbi decoder/12-way deinterleaver 901identifies the normal symbol and the enhanced symbol from each otherbased on the E8-VSB data symbol attribute and then performs Viterbidecoding correspondingly. And, the Viterbi decoder/12-way deinterleaver901 performs deinterleaving to output a result of byte unit to the ATSCdata byte deinterleaver 902. And, 8-level decision value from theViterbi decoder during decoding is fed back to the equalizer 604. TheATSC data byte deinterleaver 902 deinterleaves the data of byte unitoutputted from the Viterbi decoder/12-way deinterleaver 901.

Namely, the ATSC data byte deinterleaver 902 outputs the data of byteunit in a manner of performing deinterleaving on the output of theViterbi decoder/12-way deinterleaver 901 according to a process reverseto that of the ATSC byte interleaver in FIG. 3. The deinterleaved datacan be divided into 188-byte packet units and can be separated into anormal data packet and an enhanced data packet. The data outputted fromthe ATSC data byte deinterleaver 902 is identically inputted to the ATSCRS decoder 903 and the ATSC RS parity removing unit 951 of the enhanceddata decoding unit 950.

The ATSC RS decoder 903 performs RS decoding on the data packet, whichis the output of the ATSC data byte deinterleaver 902, according to aprocess reverse to that of the ATSC RS coder in FIG. 3, and then outputsthe result to the ATSC data derandomizer 904.

The output of the ATSC data derandomizer 904 is finally outputted as anMPEG TPS #1. Since the enhanced data packets are encapsulated with nullPID, the enhanced packets multiplexed in the output of the dataderandomizer 904 can be discarded, and so there is no problem inreceiving normal packets in the conventional AV (audio/video) decoder.

The ATSC RS parity removing unit 951 of the enhanced data decoding unit950 removes an ATSC RS party portion from the output of the ATSC databyte deinterleaver 902 and then outputs the result to the ATSC dataderandomizer 952. Namely, since the ATSC parity portion is not used inthe enhanced data decoding, it can be removed.

The ATSC data derandomizer 952 derandomizes the data of which ATSC RSparity portion was removed in a process reverse to that of the ATSCrandomizer 302-1 in FIG. 3 and then outputs the result to the null-bitremoving unit 953.

The E8-VSB data attribute generator 705 identifies whether the outputfrom the ATSC data derandomizer 952 is a normal data byte or en enhanceddata byte. If it is the byte for enhanced data, the E8-VSB dataattribute generator 705 further identifies whether the enhanced databyte is a byte for the ½ enhanced data or a byte for the ¼ enhanceddata. The null-bit removing unit 953 removes the entire normal databytes (including MPEG header bytes added to an enhanced data packet) andthe null bits inserted to the enhanced data byte to reconfiguremeaningful bytes and then outputs the reconfigured bytes to the enhanceddata deinterleaver 954. In doing so, the VSB byte attribute informationoutputted from the main and enhanced mux packet processor 957 enables toidentify whether each byte is for the normal data stream, the ½ enhanceddata byte, or the ¼ enhanced data byte.

First of all, in case of the normal data byte, the respective bits arecompletely removed. In doing so, having the attribute of normal data,the MPEG header inserted in the ½ or ¼ enhanced data packet is removedas well. Meanwhile, in case of the enhanced data byte, reconfigurationsare performed as shown in FIG. 13 and FIG. 14. Hence, the null-bitremoving unit 953 ignores the normal data and outputs the null-bitremoved ½ and ¼ enhanced data only.

Namely, in case of the ½ enhanced data, since one byte, as shown in (b)of FIG. 13, is expanded to 2 bytes by inserting the null bits in theE8-VSB transmission system, the insignificant bits (i.e., null bits) areremoved in (b) of FIG. 13 to reconfigure one significant byte in (a) ofFIG. 13. In case of the ¼ enhanced data, each bit, as shown in (b) ofFIG. 14, is repeated and null-bits are inserted for a 4-byte expansion.Hence, the insignificant bits (i.e., repeated bits and null bits) areremoved from (b) of FIG. 14 to reconfigure the four consecutive ¼enhanced data bytes into one significant byte shown in (a) of FIG. 14.

The enhanced data deinterleaver 954 performs deinterleaving on enhanceddata byte consisting of significant bits outputted from the null-bitremoving unit 953 in a manner reverse to that of the enhanced datainterleaver 505 in FIG. 6 and then outputs the deinterleaved data to theenhanced RS decoder 955. The enhanced RS decoder 955 performs decodingon the deinterleaved data in a manner reverse to that of the enhanced RScoder 504 in FIG. 6 and then outputs the decoded data to the enhancedpacket demultiplexer 956.

The enhanced packet demultiplexer 956 separates the enhanced RS decodeddata into a ½ enhanced data packet of 164-byte unit and a ¼ enhanceddata packet of 164-byte unit using the E8-VSB map information and fieldsync signal outputted from the E8-VSB map recovery 605 and then outputsthem as MPEG TPS #2 and MPEG TPS #3, respectively. The separation schemeis explained with reference to FIG. 15 and a method of generating theenhanced packet having the enhanced data attribute information isexplained with reference to the enhanced packet generator in FIG. 12.Thus, by receiving the E8-VSB signal, it is able to receive the normaldata MPEG TPS #1, the ½ enhanced data MPEG TPS #2, and the ¼ enhanceddata MPEG TPS #3.

Namely, the main and enhanced mux packet processor 801 in FIG. 10performs the same operation of the main and enhanced mux packetprocessor 957 in FIG. 11. The corresponding detailed diagram of the mainand enhanced mux packet processor is shown in FIG. 12.

In the present invention, the main and enhanced mux packet processorsare provided to the E8-VSB data attribute generator 705 and the E8-VSBchannel decoder/demultiplexer 606, respectively. Alternatively, one mainand enhanced mux packet processor is provided to the present inventionso that an output of the main and enhanced mux packet processor can beused in both the E8-VSB data attribute generator 705 and the E8-VSBchannel decoder/demultiplexer 606.

FIG. 12 is a detailed block diagram of the main and enhanced mux packetprocessor 801 or 957.

The main and enhanced mux packet processor generates attributeinformation of E8-VSB data of byte unit using the E8-VSB map informationof the current field decided by the current map deciding unit 703 of theE8-VSB map recovery 605 and the field sync signal recovered by the framesync recovery 704. The attribute information of E8-VSB data of byte unitprovides information of whether the current byte is the normal data byteor the enhanced data byte. If the current byte is the enhanced VSB byte,the attribute information also provides information of whether theenhanced data byte is the ½ enhanced data byte coded at ½ code rate orthe ¼ enhanced data byte coded at ¼ code rate.

For this, the main and enhanced mux packet processor includes anenhanced packet generator 1011, a null enhanced RS coder 1012, anenhanced data interleaver 1013, a null-bit expander 1014, a null MPEGheader inserter 1015, and a main and enhanced packet multiplexer 1016.

Namely, the enhanced packet generator 1011 generates an attribute packethaving the attribute information of whether the enhanced data is the ½enhanced data or the ¼ enhanced data. By the E8-VSB map information ofthe current field, the distributions and rates of the ½ and ¼ enhanceddata packets of the current field are determined. In accordance with thetwo distribution types, FIG. 15A and FIG. 15B show a case that thenumber of packets of the ½ enhanced data is eight and the number ofpackets of the ¼ enhanced data is two. Namely, FIG. 15A shows an examplethat the ½ enhanced data packets and the ¼ enhanced data packets areseparately grouped to be multiplexed (grouping multiplexing) and FIG.15B shows an example that the ½ enhanced data packets and the ¼ enhanceddata packets are alternately multiplexed one by one (alternatemultiplexing).

In doing so, the enhanced packet generator 1011 generates an attributesignal for whether each enhanced packet has the attribute of ½ or ¼rather than a signal including significant data. The attribute signalenables to output an attribute of E8-VSB data byte via the null enhancedRS coder 1012, enhanced data interleaver 1013, null bit expander 1014,null MPEG header inserter 1015, and main and enhanced packet multiplexer1016.

Namely, an attribute packet of 164 bytes having the attributeinformation of the enhanced data outputted from the enhanced packetgenerator 1011 is inputted to the null enhanced RS coder 1012. The nullenhanced RS coder 1012 adds a parity of 20 bytes to the receivedattribute packet of 164 bytes to output an attribute packet of 184bytes. In doing so, the parity added to the parity area is forjustification. Hence, the attribute of each packet is copied as many asa parity amount for expansion. Namely, although the parity generatedfrom performing substantial enhanced RS coding is added in a normal datapath, the expansion is performed by the null enhanced RS coder 1012 in amanner of copying the attribute of each packet to the parity area asmany as the parity amount.

An output of the null enhanced RS coder 1012 is inputted to the enhanceddata interleaver 1013 for interleaving and the interleaved output isoutputted to the null bit expander 1014. The interleaving is achieved inthe same manner of the enhanced data interleaver 505.

The null bit expander 1014, as shown in FIG. 13 or FIG. 14, expands theinterleaved byte outputted from the enhanced data interleaver 1013 tofit the ½ or ¼ enhanced data. Namely, if the byte from the enhanced datainterleaver 1013 is the byte having the ½ attribute information and hasthe configuration shown in (a) of FIG. 13, the null bit expander 1014,as shown in (b) of FIG. 13, inserts null bits in the byte to expand totwo bytes. If the byte from the enhanced data interleaver 1013 is thebyte having the ¼ attribute information and has the configuration shownin (a) of FIG. 14, the null bit expander 1014 performs bit repetitionand null bit insertion to expand the byte to 4 bytes. The null bitexpander 1014 then outputs the expanded bytes to the null MPEG headerinserter 1015. In doing so, since the expanded byte means the attributeof the enhanced data, values of b7 to b0 are identical to each otherunlike the null bit expander of the transmitter.

The null MPEG header inserter 1015 adds a value, which indicates thenormal data byte corresponding to an MPEG header, in front of each 184bytes outputted from the null bit expander 1014 and then outputs thecorresponding result to the main and enhanced packet multiplexer 1016.The main and enhanced packet multiplexer 1016, which outputs packets by188-byte packet unit, multiplexes the normal data packets and theenhanced data packets to output. In doing so, the main and enhancedpacket multiplexer 1016 seeks the number H of the ½ enhanced datapackets of 188-byte unit and the number Q of the ¼ enhanced data packetsof 188-byte unit from the E8-VSB map information based on the field syncsignal outputted from the E8-VSB map recovery 605 and then finds thenumber 2P of packets of 188-byte unit allocated to the enhanced data perone VSB field (2P=2H+4P).

The main and enhanced packet multiplexer 1016 multiplexes the normaldata packets and the enhanced data packets using a multiplexing rulebased on the distribution method selected in the E8-VSB map information.For example, if a pattern distribution method is selected, themultiplexing rule shown in FIG. 16A may be used. In this rule, positionsof the enhanced data packet in a data field are assigned to every fourthsegment starting from at least one predetermined start position (segmentposition 0, 2, 1, and/or 3) within the data field.

On the other hand, if an even (uniform) distribution method is selected,the multiplexing rule shown in FIG. 16B may be used. “s” shown in bothrules denotes a packet (or segment before ATSC byte interleaving)position for an enhanced data packet with respect to a fieldsynchronizing signal within the data field. By outputting a signalindicating the normal data byte in case of a normal data packet oroutputting a signal from the null MPEG header inserter 1015 in case ofan enhanced data packet, the final E8-VSB data byte attribute isoutputted.

As mentioned in the foregoing description of the digital E8-VSBreception system and E8-VSB data demultiplexing method according to thepresent invention, the enhanced data are coded at ½ code rate and ¼ coderate in the new E8-VSB transmission system compatible with theconventional ATSC 8VSB system, respectively. The ½ and ¼ enhanced dataare multiplexed by 164-byte packet unit according to the previouslydetermined multiplexing format and further pre-processed to output asthe format of the MPEG transport packet. And, the pre-processed enhanceddata and the main data are multiplexed again by 188-byte packet unitaccording to the previously determined multiplexing format. In such acase, the E8-VSB reception system according to the present inventionenables to completely receive both of the ATSC 8VSB signal and theE8-VSB signal.

Moreover, the E8-VSB map information, which was inserted in the fieldsync section in the E8-VSB transmission system to be transmitted, isextracted to generate the information indicating the attributes of therespective E8-VSB data. The normal data, ½ enhanced data, and ¼ enhanceddata are separated from each other to be decoded in the channel decoder.And, the E8-VSB data symbol attribute is used in channel equalization.Therefore, the present invention improves the performance of theequalizer, thereby enabling to enhance the performance of the E8-VSBreception system.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present invention. Thus,it is intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A method of processing broadcast data in a digital television (DTV) transmitter, the method comprising: randomizing enhanced data; first RS encoding the randomized enhanced data; first interleaving the first RS-encoded enhanced data; deinterleaving the first interleaved enhanced data; second RS encoding the deinterleaved enhanced data; second interleaving the second RS-encoded enhanced data; trellis encoding the interleaved enhanced data; and transmitting a broadcast signal including the trellis-encoded enhanced data, wherein the broadcast signal further includes main data.
 2. The method of claim 1, further comprising: converting symbols corresponding to the first interleaved enhanced data into bytes corresponding to the first interleaved enhanced data.
 3. The method of claim 1, further comprising: multiplexing the trellis encoded enhanced data with segment and field synchronization data.
 4. A digital television (DTV) transmitter comprising: a randomizer configured to randomize enhanced data; a first encoder configured to first RS-encode the randomized enhanced data; a first interleaver configured to first interleave the first RS-encoded enhanced data; a deinterleaver configured to deinterleave the first interleaved enhanced data; a second encoder configured to second RS-encode the deinterleaved enhanced data; a second interleaver configured to second interleave the second RS-encoded enhanced data; a trellis encoder configured to trellis-encode the interleaved enhanced data; and a transmitting unit configured to transmit a broadcast signal including the trellis-encoded enhanced data, wherein the broadcast signal further includes main data.
 5. The DTV transmitter of claim 4, further comprising: a converter configured to convert symbols corresponding to the first interleaved enhanced data into bytes corresponding to the first interleaved enhanced data.
 6. The DTV transmitter of claim 4, further comprising: a multiplexer configured to multiplex the trellis encoded enhanced data with segment and field synchronization data. 